108-47-4Relevant articles and documents
Flow synthesis of 2-methylpyridines via α-methylation
Manansala, Camille,Tranmer, Geoffrey K.
, p. 15797 - 15806 (2015)
A series of simple 2-methylpyridines were synthesized in an expedited and convenient manner using a simplified bench-top continuous flow setup. The reactions proceeded with a high degree of selectivity, producing α-methylated pyridines in a much greener fashion than is possible using conventional batch reaction protocols. Eight 2-methylated pyridines were produced by progressing starting material through a column packed with Raney nickel using a low boiling point alcohol (1-propanol) at high temperature. Simple collection and removal of the solvent gave products in very good yields that were suitable for further use without additional work-up or purification. Overall, this continuous flow method represents a synthetically useful protocol that is superior to batch processes in terms of shorter reaction times, increased safety, avoidance of work-up procedures, and reduced waste. A brief discussion of the possible mechanism(s) of the reaction is also presented which involves heterogeneous catalysis and/or a Ladenberg rearrangement, with the proposed methyl source as C1 of the primary alcohol.
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Myerly,Weinberg
, p. 2008 (1966)
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Bimetallic C-C Bond-Forming Reductive Elimination from Nickel
Xu, Hongwei,Diccianni, Justin B.,Katigbak, Joseph,Hu, Chunhua,Zhang, Yingkai,Diao, Tianning
, p. 4779 - 4786 (2016)
Ni-catalyzed cross-coupling reactions have found important applications in organic synthesis. The fundamental characterization of the key steps in cross-coupling reactions, including C-C bond-forming reductive elimination, represents a significant challenge. Bimolecular pathways were invoked in early proposals, but the experimental evidence was limited. We present the preparation of well-defined (pyridine-pyrrolyl)Ni monomethyl and monophenyl complexes that allow the direct observation of bimolecular reductive elimination to generate ethane and biphenyl, respectively. The sp3-sp3 and sp2-sp2 couplings proceed via two distinct pathways. Oxidants promote the fast formation of Ni(III) from (pyridine-pyrrolyl)Ni-methyl, which dimerizes to afford a bimetallic Ni(III) intermediate. Our data are most consistent with the subsequent methyl coupling from the bimetallic Ni(III) to generate ethane as the rate-determining step. In contrast, the formation of biphenyl is facilitated by the coordination of a bidentate donor ligand.
Transformations of pyridine bases on a nickel-aluminum catalyst
Antonova,Ovchinnikova,Bespalov,Serova,Promonenkov,Ustavshchikov
, p. 280 - 283 (1982)
The electronic structures of some pyridine bases are analyzed by means of 1H and 13C NMR spectroscopic data for substituted pyridines and the calculated bond orders in the pyridine ring. The differences in the chemical bonds in the pyridine ring of isomeric methylpyridines and the carbon-carbon bonds between the ring and the methyl groups in these compounds are in agreement with the experimental data on the thermal stability of the simplest pyridine bases and the gas-phase transformation of the isomeric methylpyridines on an industrial nickel-aluminum catalyst. The possibility of obtaining mono- or dialkylpyridines under these conditions, depending on the structure of the starting pyridine bases, is demonstrated.
A mild and efficient H2O2 oxygenation of N-heteroaromatic compounds to the amine N-oxides and KI deoxygenation back to the tertiary amine with hexaphenyloxodiphosphonium triflate
Khodaei, Mohammad Mehdi,Alizadeh, Abdolhamid,Hezarkhani, Hadis Afshar
, p. 1843 - 1849 (2018/07/06)
A mild and efficient method for the oxidation of N-heteroaromatic compounds to the corresponding N-oxides using H2O2 in the presence of hexaphenyloxodiphosphnium triflate (Hendrickson reagent) in EtOH at room temperature was reported. This methodology presented relatively fast and selective reactions to afford the N-oxides in good yields. The reverse reactions, deoxygenation reactions, were also carried out under the same reaction conditions by KI to produce the tertiary amines.
